(US10012675)A standard sample (72) that is a nanometer standard prototype, having a standard length that serves as a length reference, includes a SiC layer in which a step-terrace structure is formed. The height of a step, used as the standard length, is equal to the height of a full unit that corresponds to one periodic of a stack of SiC molecules in a stack direction or equal to the height of a half unit that corresponds to one-half periodic of the stack of SiC molecules in the stack direction. In a microscope such as an STM to be measured in a high-temperature vacuum environment, heating in a vacuum furnace enables surface reconstruction with ordered atomic arrangement, while removing a natural oxide film from the surface, so that accuracy of the height of the step is not degraded. Accordingly, a standard sample usable under a high-temperature vacuum is achieved.

特許請求の範囲（英語）

[claim1]1. A nanometer standard prototype having a standard length that serves as a length reference, the nanometer standard prototype comprising a substrate that includes a single crystal SiC layer in which a step-terrace structure is formed, the height of a step formed in the SiC layer being equal to the height of a full unit that corresponds to one periodic of a stack of single crystal SiC molecules in a stack direction or equal to the height of a half unit that corresponds to one-half periodic of the stack of single crystal SiC molecules in the stack direction, the height of the step being used as the standard length.[claim2]2. The nanometer standard prototype according to claim 1, wherein an off angle is provided on a (0001) Si face or a (000-1) C face of the SiC layer of 4H or 6H polytype, a heat treatment is performed on the substrate under Si vapor pressure in a temperature range of 1500 deg. C. or more 2300 deg. C. or less, to cause a surface of the substrate to be vapor-etched and planarized to a molecular level and to form a step corresponding to one periodic or one-half periodic of a single crystal SiC molecular arrangement so that a step-terrace structure that is in conformity with the off angle is formed in the surface of the substrate.[claim3]3. The nanometer standard prototype according to claim 2, wherein the heat treatment for the formation of the step-terrace structure is performed in a container made of tantalum metal and including a tantalum carbide layer that is exposed in an internal space of the container.[claim4]4. The nanometer standard prototype according to claim 1, wherein the SiC layer is made of 4H-SiC single crystal or 6H-SiC single crystal.[claim5]5. The nanometer standard prototype according to claim 1, wherein adjusting an off angle of a surface in which the step-terrace structure is formed allows formation of a terrace having any terrace width.[claim6]6. The nanometer standard prototype according to claim 1, wherein a surface of the substrate is a (0001) Si face of the SiC layer of 4H or 6H polytype, a heat treatment is performed on the substrate under Si vapor pressure in a temperature range of 1500 deg. C. or more 2300 deg. C. or less, to cause the surface of the substrate to be vapor-etched and planarized to a molecular level and to form a step-terrace structure in the surface of the substrate, each terrace having a surface configuration in which a (2Root 3 * 2Root 3)-30 deg. pattern or a (62Root 3 * 62Root 3)-30 deg. pattern including a single crystal SiC molecular arrangement structure is formed.[claim7]7. The nanometer standard prototype according to claim 6, wherein even when the substrate is maintained in the atmosphere so that a natural oxide film is formed on a surface of the SiC layer, heating the substrate in a vacuum state in a temperature range of 800 deg. C. or more and 1400 deg. C. or less causes the natural oxide film to be removed from the surface of the SiC layer and causes a reconstruction of the single crystal SiC molecular arrangement formed on the surface of the SiC layer to occur so that a (2Root 3 * 2Root 3)-30 deg. pattern or a (62Root 3 * 62Root 3)-30 deg. pattern is formed.[claim8]8. The nanometer standard prototype according to claim 7, wherein a predetermined off angle is provided on the (0001) Si face that is the surface of the substrate before planarization of the SiC layer, so that a step-terrace structure is formed in the surface of the substrate at a time of planarization of the SiC layer.[claim9]9. The nanometer standard prototype according to claim 6, wherein the substrate is a conductive substrate given a resistivity of 0.3 OMEGA cm or less by doping of an impurity.[claim10]10. The nanometer standard prototype according to claim 1, wherein the step-terrace structure is formed in both a Si-surface and a C-surface of the substrate.[claim11]11. The nanometer standard prototype according to claim 1, wherein the nanometer standard prototype is used as a standard sample for calibration of a measuring instrument.[claim12]12. A method for manufacturing a nanometer standard prototype configured such that a step-terrace structure is formed on a substrate whose surface includes a single crystal SiC layer, the height of a step is equal to the height of a full unit that corresponds to one periodic of a stack of single crystal SiC molecules in a stack direction or equal to the height of a half unit that corresponds to one-half periodic of the stack of single crystal SiC molecules in the stack direction, and the height of the step is used as a standard length, the method comprising: an off-angle providing step of providing an off angle on a (0001) Si face or a (000-1) C face of a surface of a substrate of 4H or 6H polytype; and a step-terrace structure formation step of forming a step-terrace structure that is in conformity with the off angle in the surface of the substrate by performing a heat treatment on the substrate under Si vapor pressure in a temperature range of 1500 deg. C. or more 2300 deg. C. or less, to cause the surface of the substrate to be vapor-etched and planarized to a molecular level and to form a step corresponding to one periodic or one-half periodic of a single crystal SiC molecular arrangement.[claim13]13. A method for manufacturing a nanometer standard prototype configured such that a step-terrace structure is formed on a substrate whose surface includes a single crystal SiC layer, the height of a step is equal to the height of a full unit that corresponds to one periodic of a stack of single crystal SiC molecules in a stack direction or equal to the height of a half unit that corresponds to one-half periodic of the stack of single crystal SiC molecules in the stack direction, and the height of the step is used as a standard length, the method comprising: an off-angle providing step of providing an off angle on a (0001) Si face that is the surface of the substrate; and a surface configuration formation step of performing a heat treatment on the substrate under Si vapor pressure in a temperature range of 1500 deg. C. or more 2300 deg. C. or less, to cause the surface of the substrate to be vapor-etched and planarized to a molecular level and to form a step corresponding to one full unit or half-unit cell height of a single crystal SiC molecular arrangement so that a step-terrace structure that is in conformity with the off angle is formed in the surface of the substrate, and forming, in each terrace, a surface configuration having a (2Root 3 * 2Root 3)-30 deg. pattern or a (62Root 3 * 62Root 3)-30 deg. pattern including a single crystal SiC molecular arrangement structure, wherein, even when the substrate is maintained in the atmosphere so that a natural oxide film is formed on a surface of the SiC layer, heating the substrate in a vacuum state in a temperature range of 800 deg. C. or more and 1400 deg. C. or less causes the natural oxide film to be removed from the surface of the SiC layer and causes a reconstruction of the single crystal SiC molecular arrangement formed on the surface of the SiC layer to occur so that a (2Root 3 * 2Root 3)-30 deg. pattern or a (62Root 3 * 62Root 3)-30 deg. pattern is formed.[claim14]14. The method for manufacturing the nanometer standard prototype according to claim 12, wherein the nanometer standard prototype is used as a standard sample for calibration of a measuring instrument.[claim15]15. The method for manufacturing the nanometer standard prototype according to claim 13, wherein the nanometer standard prototype is used as a standard sample for calibration of a measuring instrument.[claim16]16. The nanometer standard prototype according to claim 6, wherein the step-terrace structure is formed in both a Si-surface and a C-surface of the substrate.[claim17]17. The nanometer standard prototype according to claim 6, wherein the nanometer standard prototype is used as a standard sample for calibration of a measuring instrument.